The use of measuring coils is state of the art for measuring a magnetic field change due to torque on the basis of magnetostriction. The coils are installed in a contactless way in relation to a magnetically coded measuring shaft (in parallel to the rotary axis) and record magnetic field changes that occur due to the magnetoelastic effect under load (inverse magnetostriction). The magnetic field change is directly proportional to the external force impact and establishes the link to the torque.
Recording of a twisting angle is state of the art for torque measurements by means of Anisotropic MagnetoResistance (AMR) sensors. An AMR sensor is a magnetic field sensor that can measure the magnetic field strength based on the anisotropic magnetoresistive effect (AMR effect). At an end of the torsion track over which the torque is to be measured, a magnetic multipole ring, which is located opposite to an AMR sensor, is installed. Twisting of the torsion track leads to a movement of the multipole ring in relation to the AMR sensor, wherein the direction of the magnetic field at the location of the sensor changes. Out of this connection between the twisting angle and the magnetic angle, the torque is subsequently determined.
The currently used methods, however, come with some disadvantages. Measurement coils only have a sensitive axis because they can only measure magnetic field changes along their longitudinal axis. Magnetic field changes in other directions can therefore not be recorded. In this process, for example additional information about the external force impact or an external magnetic field are getting lost. In case of torque measurement by means of AMR sensors, the pole ring has to be coupled with the shaft, which is structurally complex.
In view of these disadvantages, the present disclosure has the purpose of providing a method that allows for better recording of magnetic field changes and a more accurate conversion into torque and/or that constitutes a structural simplification.